1. Field of the Invention
The present invention relates to an electric connector that connects a flexible wiring substrate (FPC), a flexible flat cable (FFC), or the like.
2. Description of the Related Art
As one example of an electric connector of this type, connectors for FPC described in Patent Literature 1 and Patent Literature 2 described below have been known. In a connector for FPC shown in FIG. 5, for example, many flat metal contacts (electrically conductive terminals) with an approximately H shape 1 are attached within a hollow insulating housing 2 in a row manner at proper small pitch, and an actuator 4 is pivotally attached to a rear end of the insulating housing 2 via a pivoting shaft 3.
At that time, each of the above-described contacts 1 has a fixed beam 1a and a movable beam 1b extending in an insertion direction of an FPC which is a connection object, or an object to be connected, (not shown), and the movable beam 1b disposed on an upper side in FIG. 5 is swingably connected to the fixed beam 1a via a coupling spring portion 1c. When a portion to be operated 1d provided on a rear end portion of the movable beam 1b is deformed elastically so as to be lifted up according to pivoting of a cam portion 4a provided on the actuator 4, a contact portion 1e provided on a front end portion of the movable beam 1b is pushed on the FPC which is the connection object so that the FPC is clamped between a contact portion 1f of the fixed beam 1a and the contact portion 1e. 
In such a conventional electric connector, however, the coupling spring portion 1c joining the fixed beam 1a and the movable beam 1b to each other is formed in a straight shape connecting the both the beams 1a and 1b to each other approximately linearly. Therefore, according to advance of thinning or height reducing of an electric connector in recent years, a span length of the coupling spring portion 1c having a straight shape is shortened correspondingly. As a result, deformation stress generated when the movable beam 1b is displaced so as to be connected with a connection object such as an FPC concentrates on the coupling spring portion 1c and the coupling spring portion 1c plastically deforms, which may result in loss in required elasticity.
In view of these circumstances, in an electric connector shown in FIG. 6, for example, a constitution that a span length is elongated by bending a coupling spring portion 1g in a crank shape is adopted, so that concentration of deformation stress such as described above is avoided (see Patent Literature 3 described below). In an electric connector adopting such a constitution, however, since the coupling spring portion 1g extending from a fixed beam 1a is formed so as to extend toward a connector front end (a right side in FIG. 6) inserted with a connection object such as an FPC, an arrangement space for the coupling spring portion 1g is expanded and a length of a portion to which a connection object such as an FPC is inserted is shortened, which results in a problem that an insertion guide length and an effective fitting length of a connection object become insufficient.
In the electric connector shown in FIG. 6 and described above, therefore, an insertion space of a connection object is secured by biasing an arrangement position of the coupling spring portion 1g toward a connector rear end (a left side in FIG. 6). In such a constitution, however, a distance X from a swinging center W of the movable beam 1b to an FPC contact point P on a front end side is considerably larger than a distance Y from the same swinging center W to an actuator operating point Q that is a pivoting center of an actuator 3 (X>Y). Therefore, a working amount at the FPC contact point P of the movable beam 1b to an operation amount of the actuator 3 is largely expanded. As a result, large fluctuation in a contact pressure of the movable beam 1b to an FPC occurs, which may result in lowering in reliability of the electric connector.
It is thought that the distance X to the FPC contact point P and the distance Y to the actuator operating point Q are set to be approximately equal to each other by setting the swing center W of the movable beam 1b to an approximately central position of the fixed beam 1a (X≅Y). In that case, however, the insertion space for a connection object can not be secured, as described above. Otherwise, the connector must be extended in an insertion direction of the connection object in order to secure the insertion space for a connection object, which results in large-sizing of the connector.
In the conventional electric connector, as shown in FIG. 5, since the fixed beam 1a is attached to the insulating housing 2 in a completely fixed state, when a connection object such as, for example, an FPC is applied with a deformation force acting upward in FIG. 5, the movable beam 1b also elastically deforms upwardly following the connection object such as an FPC. However, since the fixed beam 1a is fixed to the insulating housing 2 and it is not deformed, a contact pressure to the connection object becomes unstable due to separation of the contact portion 1f at a distal end thereof from the connection object such as an FPC. Particularly, when the connection object is a lower contact, electrical conduction may be shut off instantaneously.
Patent Literature 1: Japanese Patent No. 3047862
Patent Literature 2: Japanese Patent No. 3101951
Patent Literature 3: JP-A-11-307198
An object of the present invention is to provide an electric connector which can maintain an excellent contact state of a movable beam and a fixed beam to a connection object such as an FPC utilizing a simple structure.